Abstract
Protein C, a potent vitamin K dependent protein, which is activated by the endothelial cell cofactor thrombomodulin, plays a major role in anticoagulant and profibrinolytic activity. We have studied the changes in protein C (PC) activity in septic patients. Samples were collected from 30 septic patients who fulfilled the criteria of systemic inflammatory response syndrome (SIRS) for more than 3 consecutive days. Among these patients, 4 developed DIC (DIC group), 11 multiple organ dysfunction other than DIC (MODS group) and 15 had no complications (SIRS group). The results showed that PC activities on the third day after the onset of SIRS in the DIC group (47.3±23.3%) and MODS group (32.0±9.0%) were significantly lower than that of the SIRS group (68.9±22.5%, p<0.01 respectively). Chronological PC activity changes in the SIRS group showed recovery by the seventh day after the onset of SIRS. On the other hand, these recoveries were not recognized in many of the cases in the MODS and DIC groups. A strong correlation was recognized between PC activity and protein C antigen (r=0.91, p<0.01). A negative relationship was recognized between plasma thrombomodulin and PC activity (r=-0.48, p<0.01), and between plasminogen activator inhibitor-1 and PC activity (r=-0.40, p<0.05). A weak but positive correlation was observed between PC activity and plasmin-plasmin inhibitor complex (r=0.31, p<0.01). On the other hand, no correlation was observed between PC activity and thrombin-antithrombin III complex or between PC activity and tissue factor. Marked reduction in functional activity of protein C may contribute to development of the thromboembolic complications often observed in patients with severe sepsis.
